Weekly injectable implant may be ‘game-changer for Parkinson’s care’
Its steady release of levodopa-carbidopa helps reduce off times, side effects
A weekly injectable implant could make treatment for Parkinson’s disease easier and more effective by steadily releasing levodopa and carbidopa into the bloodstream and replacing the need to take the medications multiple times a day, according to a study led by the University of South Australia (UniSA).
“Our goal was to create a formulation that simplifies treatment, improves patient compliance, and maintains consistent therapeutic levels of medication. This weekly injection could be a game-changer for Parkinson’s care,” Sanjay Garg, PhD, a professor at UniSA who led the study, said in a university press release.
The study, “Development of an in-situ forming implant system for levodopa and carbidopa for the treatment of Parkinson’s disease,” was published in Drug Delivery and Translational Research.
Parkinson’s disease develops as the brain gradually loses dopamine, a chemical essential for controlling movement. The primary treatment is levodopa, a medication the body converts into dopamine. It is typically combined with carbidopa, which prevents levodopa from being broken down too early outside the brain, allowing more of it to reach the brain where it’s needed.
Levodopa can become less effective over time, leading to off periods
Over time, levodopa can become less effective, leading to off periods when motor symptoms return between doses, including tremor and uncontrolled movements. As a result, patients need more frequent doses of the medications, which can be challenging, especially for older people or those who have difficulty swallowing. This can lead to uneven levels of levodopa in the body, which increases the risk of side effects.
“Alternative to the existing treatment, long-acting injectables provide sustained release of the drug with constant [blood] levels of the drug while reducing the dosing frequency and side effects,” the researchers wrote.
In this study, the team combined a biodegradable material called PLGA and a pH-sensitive material called Eudragit L-100 into a gel that forms a small implant inside the body after being injected under the skin or into muscle. The gel breaks down and releases levodopa and carbidopa over time, keeping their levels steady.
The final formulation contained 26% PLGA and 6% Eudragit. When tested in the lab, it released about one-third of the medications in the first 24 hours: 34% of the levodopa and 37% of the carbidopa. By the end of one week, it had released most of the levodopa (92%) and carbidopa (81%).
Garg’s team also tested how easily the injection could be given. The formula flowed smoothly, showed consistent thickness, and was easy to inject through a standard needle. The implant broke down well in the body, losing about 82% of its weight in seven days. This means it does not need to be removed after being injected.
“After years of focused research, it’s incredibly rewarding to see our innovation in long-acting injectables for Parkinson’s disease reach this stage,” said Deepa Nakmode, a PhD student at UniSA and the first author of the study. “Our invention has now been filed for an Australian patent.”
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